Pharaoh Ant (Hymenoptera: Formicidae): Fenoxycarb Baits Affect Colony Development

Fenoxycarb, an insect growth regulator, was highly effective against the Pharaoh ant, Monomorium pharaonis (L.). Fenoxycarb acts by reducing egg production in the queens; the colonies eventually die because of worker attrition. The best laboratory results were obtained using concentrations of 0.25, 0.5, and 1% in peanut oil. These concentrations significantly reduced worker numbers by 12 wk and quantity of brood by 5 wk, if not sooner; however, more than one baiting was necessary to eliminate the colonies completely. Also, in some tests, colonies fed fenoxycarb baits at concentrations of 0.1, 0.25, and 0.5% significantly delayed the production of winged reproductives. Intermediate castes (individuals that were larger than workers yet smaller than queens) were produced at lower concentrations (0.05, 0.1, and 0.25%). Higher concentrations of 2.5 and 5% were not effective, probably because of repellency of the chemical. These results demonstrate that fenoxycarb is as effective as the commercially available bait, Pharorid (methoprene), for the control of the Pharaoh ant.